Soil management in organic rainfed vineyards in the Penedès region (Catalonia, NE Spain) with cover crops and mulches. Effects on weed flora and vine vigor

Abstract

In Mediterranean organic vineyards, repeated mechanical tillage is the standard strategy for weed control, but it contributes to soil degradation, fuel consumption, and carbon emissions. This study evaluated alternative soil management practices—cover crops in the alleyways and organic mulches under the vine row—to reduce tillage while maintaining weed suppression and vine vigor. Two field trials were conducted over two growing seasons (2021–2022), characterized by exceptionally dry conditions, in a rainfed Vitis vinifera L. cv. Chardonnay organic vineyard in the Penedès region, NE Spain. In the alleyways, two winter grasses (Hordeum vulgare and Lolium multiflorum) were sown and compared to traditional tillage management. Under the vine row, an organic pine wood chip mulch was compared to a tilled control Weed cover, vine vigor (i.e. yield, pruning weight, exposed leaf area), and canopy geometry and structure (using the principle of light detection and ranging, LiDAR) were recorded and analyzed. Cover crops effectively suppressed weeds (<10% cover), but also reduced vine vigor in both years, particularly under these extreme drought conditions. LiDAR-derived data confirmed significantly smaller canopy dimensions in vine rows bordered by cover crops compared to those between tilled alleyways. The pine mulch maintained low weed pressure and supported vine growth, showing persistence over two seasons. These results highlight the potential of organic mulching as a sustainable alternative to mechanical under-vine in-row tillage in dryland vineyards. However, the competitive impact of alleyway cover crops on vine performance must be carefully considered in water-limited environments.